Rotor for thin layer evaporator



Jan. 28, 1969 GKLOSEL 3,423,782

ROTOR FOR THIN LAYER EVAPGRATOR Filed March 21, 1967 INVENTOR. GERHARDKLOSEL BY Z WM 1 Jif /HIE):

United States Patent 2 Claims ABSTRACT OF THE DISCLOSURE coid.

The invention relates to rotors for thin layer evaporators, which havemany varied uses.

The use of versatile apparatuses for thin layer evaporation, whoseaction is based on the employment in the evaporation chamber of rotatingbodies of different construction which apply a thin layer (film) of theliquid or solution to be evaporated on to the surface which is to bevapour treated is already known. It is also known that the use of amechanical thin layer evaporator is a function of the film applicatorsystem and is based substantially on the mode of operation of two knownsystems, in which:

(a) the rotors have rigid or mobile surfaces arranged parallel to theaxis, and application of the film is effected by the centrifugal effectproduced and by action of the wiper, and

(b) the rotors have axial thrust and serve as wipers,

in a screw or spiral system.

Furthermore the rotor systems mentioned above may be distinguished fromeach other by their fundamentally difierent speeds of rotation, whichagain are characteristic of their possible uses, in that:

(a) the rotors have high speeds of rotation (surface rotors) and may beused for low consistency, nonadhering liquids or solutions; and

(b) the rotors have low speeds of rotation (screws or spiral rotors) andmay be used for high consistency, bonding liquids or solutions.

In view of the large variety of systems of materials which one wishes towork up in thin layer evaporators of this type the evaporation ofliquids or solutions which are sticky and tend to form incrustations canbe particularly difficult in the known apparatuses, in which thisproblem can only be overcome satisfactorily by use of rotors that havean axial thrust and serve as wipers. However, this arrangement is notparticularly suitable for liquid solutions which are difiicult toseparate (solutions of similar density, narrow boiling range) since theseparating effect produced by the centrifugal force of the rotatingsurfaces is absent.

The object of the invention is to overcome these disadvantages which inparticular may lead to:

(a) a narrow, and in many cases very limited, utility for differentliquids or solutions,

3,423,782 Patented Jan. 28, 1969 (b) the absence of a continuoustransition of high speed (750 to 1,500 revs/min.) to low speed (50 to750 revs/min.) film applicators,

(c) the liability of the liquids or solutions concentrated byevaporation to form accretions on the vapour treated surface and (d)contamination of the product by metal filings, due

to the grinding effect of some film applicators.

These disadvantages may be overcome according to the present inventionby providing a helix mounted on a shaft by means of radial supportsarms, in the turns of which helix are situated blades which are arrangedaxially along the shaft and offset by 180 between the individual turnsof the helix.

Preferred embodiments of the invention will now be illustrated withreference to the accompanying drawings in which:

FIG. 1 is an elevational view of a rotor,

FIG. 2 is a cross-section and FIG. 3 shows such a rotor installed in athin layer evaporator.

The rotor comprises a flat strip 2 wound round a shaft 1 a tan angle ofabout 45 thereto in the form of a helix which is fixed to the shaft 1 bymeans of distance pieces 3. Rectangular blade stumps 4 are arranged onthe shaft at intervals of 180 between the turns of the spiral. The bladestumps 4 are staggered in relation to each other in such a manner thatthe areas swept out by the blades on the evaporator cylinder 5 enclosingthem overlap each other.

It has now been found that liquids and solutions which tend to adhereand stick, and also liquid solutions of low viscosity can easily betreated by the arrangement of a helix and blade stumps according to thepresent invention, which is not the case when using the helixarrangement system alone.

I claim:

1. A rotor for thin layer evaporators, comprising a shaft with a helixattached thereto, said helix being attached to said shaft by means ofradial support arms between the turns of which helix are arranged rigidblades which are all coplanar with the shaft axis and with each otherand are arranged axially along said shaft and staggered in relation toeach other by 180 and is situated between the turns of the helix, saidblades having a radial extent at least as great as the inner diameter ofthe helix.

2. A rotor for thin layer evaporators as claimed in claim 1, comprisingsaid blades overlapping each other in the axial direction.

References Cited UNITED STATES PATENTS NORMAN YUDKOFF, Primary Examiner.

J. SOFER, Assistant Examiner.

US. Cl. X.R.

l59-6. 13; l5l04.1: 259l34

